This invention is directed to a remote passive condition sensor such as a temperature or humidity sensor. The invention is of an optical type having no electrical connection or source to a remotely located completely passive sensor.
In the prior art there has been used remotely located sensors with electrical connections extended thereto from a site where readout is desired. Other remote sensors have been electrically powered by batteries or the like and utilize radio transmission to a readout station.
The present invention described herein utilizes temperature or humidity sensors which require no electrical circuitry whatsoever and are read out by simple optical techniques to permit low cost sensing in remote or inaccessible areas.